88 research outputs found
High-frequency forcing of a turbulent axisymmetric wake
A high-frequency periodic jet, issuing immediately below the point of separation, is used to force the turbulent wake of a bluff axisymmetric body, its axis aligned with the free stream. It is shown that the base pressure may be varied more or less at will: at forcing frequencies several times that of the shear layer frequency, the time-averaged area-weighted base pressure increases by as much as 35 %. An investigation of the effects of forcing is made using random and phase-locked two-component particle image velocimetry (PIV), and modal decomposition of pressure fluctuations on the base of the model. The forcing does not target specific local or global wake instabilities: rather, the high-frequency jet creates a row of closely spaced vortex rings, immediately adjacent to which are regions of large shear on each side. These shear layers are associated with large dissipation and inhibit the entrainment of fluid. The resulting pressure recovery is proportional to the strength of the vortices and is accompanied by a broadband suppression of base pressure fluctuations associated with all modes. The optimum forcing frequency, at which amplification of the shear layer mode approaches unity gain, is roughly five times the shear layer frequency
Periodic Forcing of a Turbulent Axisymmetric Wake
Effects of variable-frequency forcing. Relation to linear theory. Effects of three-dimensional forcing. Relation between instability mechanisms. Future work includes open-loop control and feedback control
Planning southern Iraq: placing the progressive theories of Max Lock in Um Qasr, Margil, and Basra in the context of Iraqi national development, 1954â1956
Between 1954 and 1956, the architect, educator, and planner, Max Lock (1909â1988) produced a trilogy of plans to modernize the historical city of Basra and create new areas at Margil and Um Qasr in the south of Iraq. The New Basrah Plan was heavily inspired by the works of Patrick Geddes and aligned with contemporaries such as Lewis Mumford, Lockâs planning was progressive in scope and looked to differ from the planning of post-war principles in Britain through his notions of âcivic surgeryâ. Contrary to this, his plans for Um Qasr and Margil focussed on infrastructure and the creation of more industrial areas not prioritizing people and place as highly as he did in the New Basrah Plan. Lockâs âCivic Surgeryâ offered an alternative to mainstream thought by attempting to create usable, humanistic spaces, which hampered by politics and legislation, resulted in the planâs shelving and were contradicted by his other worksâ philosophies. New retrospective analysis of his underappreciated career reveals the complexities of his planning which this article demonstrates through the âfailureâ of the New Basrah Plan and his plans at Um Qasr and Margil
Clinical predictors of right upper paraesophageal lymph node metastasis from papillary thyroid carcinoma
Active control of a turbulent bluff body wake
EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Estatus Actual de los BĂșhos Terrestres (Athene cunicularia) en la Zona de Puerto LĂłpez, Ecuador: Efectos de las Creencias y Sentimientos hacĂa los Animales Silvestres
In response to negative attitudes towards the existing biodiversity in the region of Puerto Lopez, Ecuador and as a follow-up of a study conducted in 2006 on the status of Burrowing Owl (Athene cunicularia) populations, through informal interviews and observation, this investigation focuses on how local sentiments towards nature have affected the current status of the Burrowing Owl populations and their habitat. The investigation revealed that in addition to the effects of legends and beliefs, there is an existing lack of knowledge, understanding, and appreciation for the extremely high biodiversity, which has created an evident fear instilled in the people. In result, the attitudes towards wildlife have lead to destruction and have greatly impacted the populations and habitats of the Burrowing Owls. During the project, it was observed that it is possible to change negative attitudes towards nature and wildlife, although, because of the need for understanding and appreciation of the natural life in Puerto Lopez, I made some learning materials about Burrowing Owls that will be used for environmental education. In the efforts of conservation of wildlife and nature in Puerto Lopez, the most important force will be to spread knowledge about the biodiversity in order to eliminate the existing fear.
Como seguimiento a un estudio anterior y en base a algunas observaciones de sentimientos negativos hacia los animales silvestres en el cantĂłn Puerto LĂłpez, Ecuador, por medio de entrevistas y observaciones, investiguĂ© las actitudes de la gente hacĂa los animales silvestres, especĂficamente los BĂșhos terrestres (Athene cunicularia). TambiĂ©n, observĂ© el estatus actual de las poblaciones y hĂĄbitat de BĂșhos terrestres y cĂłmo estĂĄn afectados por los sentimientos de la gente de la zona. Durante el proyecto, descubrĂ, en general, un gran miedo hacĂa los animales silvestres en la regiĂłn, un miedo fundado en creencias, tradiciones, y una falta de conocimiento de la biodiversidad. Como resultado, estos sentimientos han afectado mucho el estatus actual de las poblaciones de BĂșhos terrestres, especialmente sus hĂĄbitats. AdemĂĄs, dejo algunos materiales didĂĄcticos sobre los BĂșhos terrestres que van a servir para educaciĂłn ambiental. Pueden ayudar a inculcar en los niños el reconocimiento y aprecio de la gran biodiversidad que les rodea en Puerto LĂłpez porque esta actitud es lo mĂĄs importante para los esfuerzos de conservaciĂłn de los BĂșhos terrestres y otros animales silvestres
Active control of a turbulent bluff body wake
EThOS - Electronic Theses Online ServiceGBUnited Kingdo
A Guide for Schools: Understanding and Working with Parents of Transgender Students
This dissertation fills a gap in the literature on supporting transgender students through a school-family partnership. Lack of support at home and school is directly correlated with LGBTQ studentsâ heightened risks of mental illness, contraction of HIV, incarceration, homelessness, and academic problems (Bontempo & DâAugelli, 2002; Goodenow, Szalacha, & Westheimer, 2006). Family support and acceptance helps to protect transgender youths from these negative outcomes (Bockting et al., 2013; Ryan et al, 2010; Ryan, 2009). Parents can be more effective at supporting their transgender children if they are provided with âa knowledgeable source for guidance, accurate information, and supportâ (SAMHSA, 2014, p. 2). School professionals are positioned at the intersection of schools and families and, as such, have the opportunity to serve as that much-needed source. However, no synthesized guidelines exist at this time to guide school professionals in their work with parents of transgender students. The purpose of this dissertation is to synthesize scattered recommendations into a single guide for school professionals to understanding and working with the parents of transgender students. This understanding of transgender studentsâ development, their parents, and their schools is anchored in Bronfenbrennerâs (1979) bioecological model of human development, with steps towards an effective school-family partnership framed as mesosystem interventions
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